a) Field of the Invention
The present invention relates to vehicular velocity controlling apparatus and method to follow up a preceding vehicle which is running ahead of the vehicle with an appropriate inter-vehicle distance maintained.
b) Description of the Related Art
A vehicular velocity controlling apparatus has been proposed which controls a vehicular velocity of an automotive vehicle to follow up a preceding vehicle which is running ahead of the vehicle.
In the previously proposed vehicular velocity controlling apparatus, both an inter-vehicle distance command value (which corresponds to a target inter-vehicle distance in the previously proposed vehicular velocity controlling apparatus described above) and a target relative velocity are calculated from a target inter-vehicle distance (which corresponds to an inter-vehicle distance command value) using a filter prescribed by a damping factor xcex6 and a specific angular frequency xcfx89n, a vehicular velocity command value is calculated on the basis of a detected value of the vehicular velocity, a detected value of the relative velocity, a detected value of the inter-vehicle distance, and the target vehicular velocity, and the vehicular velocity is controlled to follow up the preceding vehicle on the basis of the vehicular velocity command value. The damping factor and the specific angular frequency used by a vehicular velocity command value calculating section are determined by referring to each previously set map (memory table) on the damping factor and the specific angular frequency to be used in an inter-vehicle distance control system according to the deviation between the detected (actual) inter-vehicle distance and the relative velocity of the vehicle to the preceding vehicle by means of a control response characteristic determining section.
When the maps (two-dimensional arrays) on which a relationship between the damping factor and the specific angular frequency is prepared, each of the maps is scheduled on a presupposition that the preceding vehicle is running at a constant cruise velocity. Hence, a mismatch to the driver""s driving sense would occur when the preceding vehicle is decelerated to make a stop.
In a case where under a condition such that the preceding vehicle is interrupted from another traffic lane to the same traffic lane as the vehicle in front thereof so that the vehicle traps the preceding vehicle at an inter-vehicle distance shorter than the target inter-vehicle distance, a vehicular braking force tends to be weak and the inter-vehicle distance becomes slowly widened since the specific angular frequency and the damping factor are set such that the response to the interruption of the preceding vehicle is delayed so that a slow convergence to the target inter-vehicle distance occurs on the presupposition that the preceding vehicle is running at the constant velocity (at the cruise speed). Hence, the mismatch to the driver""s driving sense would occur.
It is, therefore, an object of the present invention to provide vehicular velocity controlling apparatus and method for an automotive vehicle which can achieve an appropriate follow-up run control to make the inter-vehicle distance appropriately equal to the target inter-vehicle distance without occurrence of the mismatch to the driver""s driving sense even if the preceding vehicle is decelerated during the follow-up run control or the preceding vehicle is interrupted into the same traffic lane as the vehicle at a shorter inter-vehicle distance than the target inter-vehicle distance.
According to one aspect of the present invention, there is provided a vehicular velocity controlling apparatus for an automotive vehicle, comprising: an inter-vehicle distance detector to detect an inter-vehicle distance from the vehicle to a preceding vehicle which is running ahead of the vehicle; a vehicular velocity detector to detect a vehicular velocity of the vehicle; a relative velocity detector to detect a relative velocity of the vehicle to the preceding vehicle; a target inter-vehicle distance calculating section that calculates a target inter-vehicle distance on the basis of detected values of the inter-vehicle distance and of the vehicular velocity; a control response characteristic determining section that determines a control response characteristic of an inter-vehicle distance system to the target inter-vehicle distance; an inter-vehicle distance command value calculating section that calculates an inter-vehicle distance command value based on the target inter-vehicle distance in accordance with the determined control response characteristic; a target vehicular velocity calculating section that calculates a target vehicular velocity on the basis of the inter-vehicle distance command value; and a vehicular velocity controlling section that controls the vehicular velocity to make the detected value of the vehicular velocity substantially equal to the target vehicular velocity, the control response characteristic determining section determining the control response characteristic in accordance with a correlation in magnitude between the target inter-vehicle distance, the inter-vehicle distance command value, and the detected value of the inter-vehicle distance.
According to another aspect of the present invention, there is provided a vehicular velocity controlling method for an automotive vehicle, comprising: detecting an inter-vehicle distance from the vehicle to a preceding vehicle which is running ahead of the vehicle; detecting a vehicular velocity of the vehicle; detecting a relative velocity of the vehicle to the preceding vehicle; calculating a target inter-vehicle distance on the basis of detected values of the inter-vehicle distance and of the vehicular velocity; determining a control response characteristic of an inter-vehicle distance system to the target inter-vehicle distance; calculating an inter-vehicle distance command value based on the target inter-vehicle distance in accordance with the determined control response characteristic; calculating a target vehicular velocity on the basis of the inter-vehicle distance command value; and controlling the vehicular velocity to make the detected value of the vehicular velocity substantially equal to the target vehicular velocity and wherein the control response characteristic determining step determines the control response characteristic in accordance with a correlation in magnitude based on the target inter-vehicle distance, the inter-vehicle distance command value, and the detected value of the inter-vehicle distance.
This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features.